Compare  issue 617168  in Chromium:

Compiling FreeType without HarfBuzz support leads to autohinter issues with ligatures. The FreeType autohinter - without HarfBuzz support - cannot support mappings through GSUB  and GPOS tables and cannot identify Latin ligatures for example as belonging to the Latin character/glyph set. 

For Chrome on Desktop, we're now compiling FreeType with HarfBuzz support. CrOS may consider doing the same, although the issue may have less impact due CrOS devices usually having HiDPI screens (?).